How linux work

 Big Picture

1. 1 Levels and Layers of Abstraction in Linux System

    User Processess(Graphical User Interface, Server, Shell)

                        >>>

                    Linux Kernel(System calls, Process Management, Memory Management, Device Drivers)

                                    >>>>

                                    Hardware(CPU, RAM, Disks, Network Port)

User space refers to the parts of main memory that the user processes can access.

1.2 Hardware : Understanding Main Memory

    the most important, in it raw form

    Each 0, 1 is called a bit, This is where the running kernel and processes reside

    collection of bits

    the CPU is an operator on memory; it read its instruction and data from the memory and writes data back  out to the memory

    the term state in reference to memory processes, the kernel and other parts of a computer system.

a state is a particular arrangement of bits. For example, if you have four bits in put memory, 

0100, 0001, 1011 represent three different states

Note 

Because it's common to refer to the state in abstract terms rather than to the actual bits, the term image refers to particular physical arrangement of bits.

1.3 The Kernel

Nearly everything that the kernel does revolves around main memory.

    The kernel is in charge of naming tasks in four general system areas:

Processes : Th eKernel is responsible for determining which processes are allow to use the CPU

Memory  :The kernel needs to keep track of a;; memory - what is currently allocated to a particular process. what might be shared between processes, and what isgree

Device Drivers

System calls and support

    1.3.1 Processes Management

        Starting, pausing, resuming, and terminating of processes

consider a system with a one-core CPU. Many processes may be able to use the CPU, but only one process may actually are the CPU at a any given time

the act of one process giving up control of the CPU to another process is called a context switch

Each piece of time called a time slice

the kernel is responsible for context switching 

1.3.2 memory management